The present invention in particular relates to an automotive electric motor for driving components or devices of an automobile. Such components or devices could, for example, be auxiliary units, actuators or pumps. The automotive electric motor according to the present invention is accordingly not an engine of the automobile for driving the vehicle. The automotive electric motor is mechanically commutated so that commutator brushes are necessary which are in permanent contact with a commutator ring. The automotive electric motor comprises a coil wire for electrically connecting the commutator brushes with a power source.
A common automotive electric motor for driving auxiliary units, actuators or pumps has an electric performance of up to approximately 500 W so that an electric current of 10 of up to 40 A with an on-board voltage of 12 or 24 V is required. The wire consequently has a diameter of at least a couple of millimeters in order to reduce the electric resistance of the coil wire. The coil wire, which can define, for example, a choke coil, therefore has a high stiffness so that it cannot be directly mechanically connected to the commutator brushes. A flexible braid wire is provided between the commutator brushes and the stiff coil wire to allow for movements of the brushes and vibrations of the coil wire. The braid wire is provided with a wire end which is electrically and mechanically connected to the coil wire by welding. The flexible braid wire can be a brush wire electrically connecting the coil wire with the commutator brush.
The stiff coil wire end is in practice defined by a machine cutting so that a burr and/or a sharp edge can result at the end surface which has been cut. The burr or sharp edge can damage the braid wire, which is connected to the coil wire, during the lifetime of the automotive electric motor. The braid wire is defined by a multiple number of thin wires each of which is sensitive to be cut by the burr or sharp edge of the coil wire. A failure of the electric motor can occur in case the braid wire is substantially severed. A failure could also occur if merely a majority of the thin wires are cut. The remaining thin wires are in this case fused due to the high electric current. The lifetime and the reliability of the automotive electric motor is consequently limited. In order to prevent such damage, additional complex manufacturing steps are necessary in order to remove the burr and sharp edges. Manufacturing costs are accordingly increased.